What are the INFINITY constants in Java, really?

Question

I just recently ran across the constants in the primitive type wrapper classes like Double.POSITIVE_INFINITY and Double.NEGATIVE_INFINITY. In the

Answer 1

The IEEE Standard 754 Floating Point Numbers states:

"The values +infinity and -infinity are denoted with an exponent of all 1s and a fraction of all 0s. The sign bit distinguishes between negative infinity and positive infinity. Being able to denote infinity as a specific value is useful because it allows operations to continue past overflow situations. Operations with infinite values are well defined in IEEE floating point."

Also: "Operations on special numbers are well-defined by IEEE. In the simplest case, any operation with a NaN yields a NaN result. Other operations are as follows:"

      Operation         Result
        n ÷ ±Infinity   0
±Infinity × ±Infinity   ±Infinity
±nonzero  ÷ 0           ±Infinity
Infinity  + Infinity    Infinity
       ±0 ÷ ±0          NaN
 Infinity - Infinity    NaN
±Infinity ÷ ±Infinity   NaN
±Infinity × 0           NaN